Effect of the Electrolyte Alkaline Ions on the Electrochemical Performance of α‐Ni(OH)2/Activated Carbon Composites in the Hybrid Supercapacitor Cell. Issue 23 (21st August 2017)

• Record Type: Journal Article
• Authors: Soserov, L.; Boyadzhieva, T.; Koleva, V.; Girginov, Ch.; Stoyanova, A.; Stoyanova, R.
• Is Part Of: ChemistrySelect. Volume 2:Issue 23(2017)
• Page Start: 6693
• Page End: 6698
• Publication Date: 2017-08-21
• Subjects: aqueous alkaline electrolyte -- energy conversion -- hybrid supercapacitor -- materials science -- nickel hydroxides; Chemistry -- Periodicals; 540.5
• DOI: 10.1002/slct.201701579
• Languages: English
• ISSNs: 2365-6549

Abstract

Abstract: Hybrid electrochemical supercapacitors supply a high energy density and reduced cycle stability. Herein, we provide new data on the effect of the Li + and K + ion from the aqueous alkaline electrolyte on the hybrid supercapacitor performance. The electrochemical cell is assembled by two dissimilar electrodes: AC versus α‐Ni(OH)2 /AC composite. Two types of alkaline electrolytes are used: individual KOH and mixed LiOH‐KOH solutions. The performance of the composite electrodes is tested by galvanostatic and cyclic voltammetry experiments. The Li + ions from the electrolyte display a positive effect on the discharge capacitance and the cycling stability of α‐Ni(OH)2 /AC. The improved performance is discussed on the basis of structure and morphology changes of the composite electrode after electrochemical testing that are probed by ex‐situ X‐ray Diffraction, Scanning Electron Microscopy and Atomic‐force Microscopy. The results show that Li + ions and H2 O from the LiOH‐KOH electrolyte are intercalated into α‐Ni(OH)2 . The surface of the composite electrode becomes smoother in the mixed electrolyte. As a result, the α‐Ni(OH)2 /AC displays an improved performance in the mixed LiOH‐KOH electrolyte than that in the individual KOH electrolyte. Abstract : We demonstrate the positive effect of the Li + ions from the alkaline electrolyte on the discharge capacitance and the cycling stability of α‐Ni(OH)2 /AC composite electrodes. This is a consequence of the preferred intercalation of Li + into α‐Ni(OH)2 leading to a smoothing of the electrode surface.